1. Field of the Invention
The present invention relates to semiconductor packages and methods of fabricating the same, and more particularly, to a semiconductor package having a cooling fan, and a method of fabricating the same.
2. Description of Related Art
A plurality of electronic components, such as CPUs or graphics cards, and a conductive circuit electrically connected to the electronic component are provided on a circuit board, such as a main board or a mother board. In operation, these electronic components generate heat. If the generated heat is not dissipated from an electronic product having the circuit board provided therein to a region outside of the electronic product, the electronic components may malfunction due to overheat. Such a problem is more and more important for electronics having increasing function requirements and higher process speed. Because the promotion of the function and process speed means that there should be more or higher level of electronic components or electronic devices integrated on the circuit board. More or higher level of electronic components or electronic devices will generate more heat. Therefore, a necessary design is to efficiently dissipate the heat generated by the circuit board.
One of heat dissipation approaches generally adopted in the industry is to provide an additional cooling fan on a main board or a mother board so as to dissipate heat generated by an electronic component and/or an electronic device. Such kind of cooling fan has been shown in U.S. Pat. Nos. 6,799,282, 7,215,548, 7,286,357 and 7,568,517.
As illustrated in FIG. 1A, a prior cooling fan is provided on a predetermined location of a circuit board and comprises a printed circuit board 11, a housing 12 and a fan wheel 13. The housing 12 has a base 120, a sleeve pipe 122 and a stator set 121 surrounding the sleeve pipe 122. The fan wheel 13 has a wheel hub 130, a magnet 131 provided on the inner side of the wheel hub 130, a plurality of blades 132 provided on the outer side of the wheel hub 130, and a shaft pillar 133 jointed to the wheel hub 130 so as to be jointed in the sleeve pipe 122. At least one control chip 110 and a plurality of passive components 112 are provided on the printed circuit board 11. The printed circuit board 11 is provided on the base 120 of the housing 12 so as to control the rotation of the fan wheel 13 by the control chip 110 such that the rotation of the fan wheel 13 drives airflow.
The control chip 110 used by the prior cooling fan illustrated in FIG. 1A is a heat generation source. If the generated heat cannot be dissipated, the control chip 110 itself will overheat and fail. Once the control chip 110 fails, the fan wheel 13 cannot operate. Therefore, heat generated by the electronic components on the mother board of the electronic product cannot be dissipated, thereby resulting in a break down or even a damaged electronics. The control chip 110 is positioned in a gap between the base 120 of the housing 120 and the wheel hub 130 of the fan wheel 13. Heat generated by the control chip 110 generally cannot be dissipated due to the narrow gap, and thus results in damaging the control chip 110 due to overheat. A cooling fan is a relatively cheaper one of parts of an electronics. However, an expensive mother board of core components of the electronics will be damaged when the cooling fan fails to work. Hence, the importance of the cooling fan is not evaluated by its price.
In addition, the provision of the control chip 110 affects the size of the gap between the wheel hub 130 of the fan wheel 13 and the base 120 of the housing 12. The height of the gap always has to be increased due to the thickness of the control chip 110 and thus is harm to the decrease of the overall height of such kind of cooling fan. And the provision of the control chip 110 will increase the required area of the printed circuit board 11. Under the condition of not expanding the cross-sectional area of such kind of prior cooling fan, if the area of the printed circuit board increases, the area of the blade should be decreased. However, the decrease of the area of the blade 132 will affect the generation of wind while insufficient wind generation will affect desired heat dissipation effect.
In order to solve the above-mentioned problems, U.S. Pat. No. 7,345,884 provides an improved cooling fan. As illustrated in FIG. 1B, the cooling fan of U.S. Pat. No. 7,345,884 is substantially the same as the previously disclosed cooling fan. The difference is that the printed circuit board 11′ forms an extension part 11a extending outside for a control chip 110′ provided thereon so as to provide the control chip 110′ outside a gap between a base 120′ of a housing 12′ and a wheel hub 130′ of a fan wheel 13′ or partially exposing the gap such that airflow driven by the fan wheel 13′ can dissipate the heat generated by the control chip 110′.
However, the formation of the above-mentioned extension part 11a of the printed circuit board 11′ will interfere the airflow driven by the fan wheel 13′ when rotating. The airflow will generate noises when being interfered, thereby affecting the utilization quality of the electronics having such kind of cooling fan provided thereon. Meanwhile, since the extension part 11a extends outside, a blade 132′ and the control chip 110′ have to remain a predetermined gap therebetween. It is harm to the decrease of the overall height of the prior cooling fan, thereby not complying with the requirement of a thin electronics.
Furthermore, for the previously disclosed prior cooling fan, the printed circuit board 11′ still needs to be provided between the wheel hub 130′ of the fan wheel 13′ and the base 120′ of the housing 12′. It is resulted in that the thickness of the printed circuit board 11′ will still affect the overall height of the cooling fan and the thin cooling fan can not be further realized.